I am trying to print a 9" x 12" postcard 2 up on a 12" x 18" sheet.

Assume there are 10 records I need order as follows

Top: 1, Bottom 6
Top: 2, Bottom 7
Top: 3, Bottom 8
Top: 4, Bottom 9
Top: 5, Bottom 10

There is not Duplex Option in Mirroring, can someone help?